In a cloud computing environment, computing is delivered as a service rather than a product, whereby shared resources, software and information are provided to computers and other devices as a metered service over a network, such as the Internet. In such an environment, computation, software, data access and storage services are provided to users that do not require knowledge of the physical location and configuration of the system that delivers the services.
The cloud computing environment may be deployed in a “hybrid cloud” topology, which is composed of two or more clouds, such as a private cloud and a public cloud, that remain distinct entities but are bound together by standardized or proprietary technology that enables data and application portability (e.g., cloud bursting for load balancing between clouds).
In the hybrid cloud topology, “cloud bursting” or “capacity scale out” may occur when an application workload (referring to the amount of processing that a hardware component has been given to do at a given time) experiences a peak load condition. “Cloud bursting” or “capacity scale out” may involve scaling out the virtual machine instances running in the private cloud by creating replications of these virtual machine instances in the public cloud to handle the peak load condition. A “capacity scale in” may involve the scaling in or the de-provisioning of these replicated virtual machine instances in the public cloud.
Typically, the decision as to whether to scale out a virtual machine instance to the public cloud during cloud bursting is based, at least in part, on the size (e.g., number of virtual cores) and current memory usage (e.g., 768 megabytes) of the virtual machine instance. If the cost is deemed acceptable, then such a virtual machine instance is scaled out. However, virtual machines may be associated with a scaling policy. A scaling policy defines the rules that will allow the virtual machine to expand or shrink their virtual resources under certain application workload demands. For example, a scaling policy may enable a virtual machine to scale out and create additional virtual machine instances in response to an increase in application workload demand.
Currently, the decision as to which virtual machine instances running in the private cloud are to be scaled out to the public cloud during cloud bursting do not take into consideration the scaling policy of the virtual machine instances. As a result, if the replicated virtual machine instance that was created in the public cloud has a scaling policy that created additional public cloud virtual machines when the application workload demand increased, then the cost of cloud bursting would be higher than anticipated. Consequently, the current cloud bursting policies are not optimized for hybrid cloud usage cost.